Broad wintering range and intercontinental migratory divide within a core population of the near-threatened pallid harrier

Abstract

Aim: To identify the migration routes and wintering grounds of the core populations of the near-threatened pallid harrier, Circus macrourus, and highlight conservation needs associated with these phases of the annual cycle. Location: Breeding area: north-central Kazakhstan; Wintering areas: Sahel belt (Burkina Faso to Ethiopia) and north-west India. Methods: We used ring recovery data from Kazakhstan and satellite tracking data from 2007 to 2008 on six adults breeding in north-central Kazakhstan to determine migration routes and locate wintering areas. In addition, one first-year male was tagged in winter 2007-2008 in India. Results: Data evidenced an intercontinental migratory divide within the core pallid harrier population, with birds wintering in either Africa or India. The six individuals tagged in north-central Kazakhstan followed a similar route (west of the Caspian Sea and Middle East) towards east Africa, before spreading along the Sahel belt to winter either in Sudan, Ethiopia, Niger or Burkina Faso. Spring migration followed a shorter, more direct route, with marked interindividual variation. The bird tagged in India spent the summer in central Kazakhstan. Half of the signal losses (either because of failure or bird mortality) occurred on the wintering areas and during migration. Main conclusions: Our study shows that birds from one breeding area may winter over a strikingly broad range within and across continents. The intercontinental migratory divide of pallid harriers suggests the coexistence of distinct migratory strategies within the core breeding population, a characteristic most likely shared by a number of threatened species in central Asia. Conservation strategies for species like the pallid harrier, therefore, require considering very large spatial scales with possibly area-specific conservation issues. We highlight urgent research priorities to effectively inform the conservation of these species. © 2011 Blackwell Publishing Ltd.